3.8-Million-Year-Old Cranium Discovered in Ethiopia

Cleveland Museum of Natural History Curator of Physical Anthropology Dr. Yohannes Haile-Selassie and his team of researchers have discovered a “remarkably complete” cranium of a 3.8-million-year-old Australopithecus anamensis specimen. This discovery has led to the disproval of a commonly accepted hypothesis about the evolution of hominins, a taxonomic tribe of primates that includes modern humans and their evolutionary ancestors. 

 

The team of experts, led by Haile-Selassie, has diligently worked at the Woranso-Mille research site in Ethiopia since 2004. It was here, in the Miro Dora locality, that the team discovered the specimen MRD-VP-1/1, referred to as “MRD,” on February 10, 2016.

 

The first piece of the specimen—the upper jaw—was found by a local Afar worker, Ali Bereino. As the team searched for more fragments, Haile-Selassie had a strong intuition that this would turn out to be a significant discovery.

 

“Ethiopia has always been labeled as the cradle of humankind, especially in the Afar region, where we have 6 million years of our evolutionary history packed in this 1-kilometer thick sediment,” he says.

 

At the Woranso-Mille research site alone, approximately 12,600 fossil specimens—including 230 hominin fossils—have been discovered. What’s more, the team was working a mere 35 miles away from Hadar, the region in which the famous “Lucy” specimen, of the Australopithecus afarensis taxon, was found. But despite this knowledge, Haile-Selassie couldn’t fathom the discovery he was about to make.

 

Upon arrival at the location of the jaw discovery, Haile-Selassie saw something globular less than ten feet away from where he was standing. Getting closer, he realized that it was a tiny braincase and hoped that it would fit with the jaw. He picked it up and sure enough, the two pieces seamlessly clicked together like puzzle pieces.  

“I couldn’t believe my eyes when I spotted the rest of the cranium,” Haile-Selassie says of this incredibly rare find. “It was a eureka moment and a dream come true.”

 

In the years following this discovery, the team conducted extensive analyses of MRD. The peer-reviewed results of these analyses have recently been published in the international scientific journal Nature, with Haile-Selassie credited as the lead researcher. 

 

Among the most significant findings was the team’s conclusion that A. anamensis and its descendant species, the well-known A. afarensis, coexisted for a period of at least 100,000 years. This finding contradicts the long-held notion of anagenesis in hominins, whereby one species disappears and gives rise to the next in a linear fashion.

 

“This is a game changer in our understanding of human evolution during the Pliocene,” says Haile-Selassie.

 

The groundbreaking investigation was no small feat. The research team, consisting of experts from across the globe, launched a joint effort to properly date the specimen and conduct extensive comparative analyses with other previously discovered and examined specimens. (For a full list of contributing authors, please visit the publication here.)

 

Dr. Beverly Saylor, of Case Western Reserve University, and her colleagues first determined the age of the fossil to be 3.8 million years by dating minerals in layers of volcanic rocks nearby. They also combined field observations with analysis of microscopic biological remains to reconstruct the landscape, vegetation, and hydrology in the area where MRD died. These results can be found in a companion paper in the same issue of Nature.

 

“MRD lived near a large lake in a region that was dry,” says Dr. Naomi Levin, a co-author on the study from the University of Michigan. “We’re eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change, and how it affected human evolution, if at all.” 

The team’s combined findings led to the assignment of the specimen to A. anamensis, the oldest known taxon within the Australopithecus genus. Additionally, due to the cranium’s rare near-complete state, the researchers identified never-before-seen facial features in the species, which was previously only known through jaw and tooth fragments. 

 

“MRD has a mix of primitive and derived facial and cranial features that I didn’t expect to see on a single individual,” says Haile-Selassie. 

 

This discovery has certainly unlocked a new understanding of human origins, though there is more research to be done. Haile-Selassie and his team will continue to search the Woranso-Mille site in hopes of finding even more clues about our ancestry. Follow developments in this remarkable story on our website and social media.

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